weft

weft is deprecated + never worked anyway

weft was a project I was eager to start but never really got anywhere. This repository has been archived but it's public in case anyone wants to critique(/learn from) my years-old non-functional code.

weft is a configuration manager for provisioning remote systems. It is powered by Fabric and is designed based on four primary guiding principles:

Server configuration is state.
State should be recorded declaratively.
Remote servers should require nothing more than a running sshd.
Changes must be pushed to remote servers.

Portability of configuration between remote operating systems is a secondary objective.

Why not...?

Why not use Puppet, or Chef, or Ansible, or Salt? Why reinvent this particular wheel?

Puppet, Chef, and Salt all run in client-server configurations, which violates principle 3 and means you have to bootstrap your bootstrap process.

Ansible is close, but thinks in very imperative terms of tasks and handlers instead of simply state.

If there are other good options out there I've missed, please let me know!

Example

Use

You have a new VM somewhere, like EC2 or Rackspace. It has whatever standard distribution. It's on, sshd is running, and you can log in as root, but that's it. What now?

$ weft sync -H weft.example.com --initial
root password: 
hostname [weft]: 
public_ip [12.34.56.78]: 
private_ip []: 172.16.12.34
...
All done! Reboot? [Yn] Y
$

All of the variables come from writing things like %{HOSTNAME:host} in your configuration files, and weft will do its best to guess defaults. These will only be requested with the --initial flag, otherwise they'll be remembered remotely.

Configuration

hosts:
  web01: 172.21.3.4
  web02: 172.21.3.5
  db01: 172.21.4.2

groups:
 - web

users:
  james:
    authorized_keys:
      - ssh-rsa AAAA....
      - ssh-rsa AAAAAAA.....
    group: web

sudoers:
 - james

packages:
 - supervisor
 - memcached
 - gcc

services:
 - memcached
 - supervisord

directories:
  /opt/web:
    user: nobody
    group: web
    permissions: 0775

files:
  /etc/ssh/sshd_config: etc/ssh/sshd_config
  /etc/sysctl.conf: etc/sysctl.conf

Concepts

Roles

While weft is certainly helpful for synchronizing the state of a single host, it's more useful to apply state (e.g. adding an SSH key or installing new nginx configs) to a set of hosts.

Weft allows specifying roles, much like Fabric. Roles group together sets of hosts, but they also group together sets of state definitions.

When synchronizing or adding a role, weft will take the union of all the roles that apply to a host. When removing a role, weft will take the union of all remaining roles and remove, stop, or undo anything in the complement.